I just put in a promo ad for Trailhead today and saw that NONE of the ads that @AlexTennant put up in February had been upvoted beyond the single vote I cast for them way back then. You'll note the following in the Community Promotion Ads - 2015 post where it says the following:
There is a minimum score threshold an answer must meet (currently 6) before it will be shown on the main site.
Gang, we're missing out on promoting our community and Salesforce Developers in general by not upvoting Promotion Ads for materials related to us and what we do! Please take the time to click on the link I've provided to the post and upvote at least some of the promo ads and/or create some additional ones if you don't like what you see.
People have complained about how poorly Salesforce is perceived as a development environment in surveys, yet we're not making any effort to put out the information in our own community to help them realize how easy it can be to learn. Let's try to change that perception by casting a vote to get some promos in place about what we do and how to learn!